Doctor-operating gear



Nov. 24, 1925.

M. OWEN DOCTOR/ OPERATING GEAR Filed June 15, 1925 2 Sheets-Sheet 1Livenion 12 0m en-W Alton/29y Nov. 24, 1925- 1,562,470

' M. OWEN DOCTOR OPERAT ING GEAR Filed June 15, 1925 2 Sheets-Sheet 2Patented Nov. 24, 1925.

UNITED STA PAT MALCOLM OWEN, on LONDON, ENGLAND.

nooron-ornnarme GEAVR. I

Application filed June 15,' 1925. Seria1 No. 37,165.

To all whom it-ma-y concern:

Be it known that I, MALCOLM OwEN, a subject of the King of GreatBritain, residing at 109 Farringdon Road, London, E. C. 1, England, haveinvented certain new and useful Improvements in Doctor-Oper ating Gears,of which the following 1s a specification. v

This invention relates to improvements in the construction of rotaryintagllo or photogravure printing machines, more especially of the typeemploying a detachable metal sheet wrapped around a prlnt ng cylinder;such machines employ a knife, commonly referred to as a scraper blade ordoctor, which scrapes the ink off the surface of the cylinder exceptwhere the engraving occurs. In the case ofa sheet wrapped around thecylinder, .a gomt occurs over which the doctor is lifted.

In machines of the class named it has hitherto been usual to bring aboutthe necessary pressure on the doctor by means of springs or weightsapplied to the pivot spindle about which the doctor works, but this isopento the objection that the pressure required causes a considerablebending of the knife between the line where it leaves its support andits contact with the; cylinder, thus requiring extra movement on theweight or spring liftin mechanism to lift the knife clear ofthe cyinder.

Unless accurate timing of the lift is provided the speeds of running themachine are much limited.

The main object of the present invention is to improve the method ofapplying pressure to a doctor so as to eliminate, uneven wear, andanother object is to improve the means of controlling the doctor so thatan efficient rise of the doctor during the passing of the joint in thecylinder surface at relatively high speed is obtainable.

1 According to the present invention an improved method of pressing thedoctor or scraping knife on to the printing surface of an intaglioprinting cylinder is employed, in flexing the knife a substantiallycontinuous line thereon beticvlveen its operating edge and its clamped ee. i

. 'Ihe flexing of the knife may. be effected by pressure from above, orby a pull from beneath, but-preferably in any case so that when thepressure is removed, the knife is the printing surface. The additionaland 'tion, a slight left in a position to wipe the cylinder andleave athin film of ink'over the whole of accurately controlled pressureapplied according to the present invention will then remove the thinfilm, 1n the engraved surface.

By judiciously applying the pressure tothe kn1 e to flex it from theinitial position when a film is left on the cylinder to the scraplngposition, the return of the knife to initial position can be obtained bythe springlness in the knife as soon as the pressure is relieved, and bythis means the doctor can be controlled so as to be lifted very quickly.'Then when the invention is applied to cylinders having a gap, that is,

printing cylinders in which the printing surface iswrapped around thecylinder, the

release of the pressure can be timed; so that leaving the ink only i theknife is retracted from the cylindert as the gap passes under it, andqulck movement of the knife, a speed something like ten thousandrevolutions er hour can be run with a large cylindhr,

whereas at present speeds only half that number are possible with themechanism at present emplo ed.

It should e understood in connection with this art that a scraper knifeas used in modern intaglio printing is very thin, say '6/1000 of aninchto get a clean, free surface during the final scraping. In practice,therefore, it'is seldom found to bequit straight on its edge, andto'leave even a thin film of any regularity all over the cylinder, for anormal setting as required according-to this invenreliminary flexingisdesirable, so that w en the final flexing occurs, the scraper has lessink to remove, and there is less movement of the scraper to non-scrapingposition. a

In the accompanyin drawings is illustrated by way of examp e onepreferred conowing to the thick only, in order struction' .for carryingthe invention into effect;

Fig. .1 is a' sideelevation showing the parts n operative position; andFig. 2 is a similar view sure gear in inoperative position;

Fig. 3 is an end elevation of the machine shown in Fig. 1; and

Figsl 4 and 5 show in side elevation and end elevation respectivelymeans for adjusting the doctor knife in its support, Fig. 5

showing the pres- N being a view from the left-hand side of.

Fig. 4.

he construction shown comprises the ordinary cross shaft 1 for a doctor2 held in initial-position by a lever 3 and spring 4: in

co-operation with an adjustable screw 5 and fixed stop 6. The spring {1pulls the screw surface of plate 1 on the cylinder 1. Such apparatusincludes a cross shaft 7 supporte in the frame 8 of the machine, abovethe doctor, and on this shaft 7 is fixed a plate 9' (see Fig. 4) whichitself is provided with w an adjustable and flexible member 10(hereafter referred to as the presser member) which bears on the doctor2'; the plate 9 is fixed to theshaft 7, which latter is square except inits bearings, by screws 83 working through slotted holes in the saidplate; the presser member 10 is preferably slotted so as to be clampedin position of adjustment between the plate 9 and a clamping bar 9 byscrews 34.

On the shaft 7 is fixed an operating arm 11 so that when the arm' 11 isrotated in a clockwise direction the plate 9will be moved so as to pressthe flexible edge of the presser member 10 on to the'doctor; thereforeit will be observed that the presser member.

10 acts as one a rml of a bell crank, of which the-other arm is themember 11. The adjustment of the member 10 relative to the doctor issuch that the pressure \on'the doctor is about midway between itsi freeor operating edge audits support 29, so as to cause the knife to bendand to give sufiicient pressure on the doctor that the latter willcompletely remove the thin film of ink, as previously mentioned.

The movement of the arm 11 and the pressure on the member 10 is obtainedby a reciprocable member, e; g., a long link 12 diametrically arrangedwith regard to the cylinder and guided, say, bya slot 13 therein passingover the cylinder shaft 14:, the re- 'duced end of which is indicated at1 1", and. supporting at its end a lever 15 carrying a slidable weight16 which is adjustable as regards its distance from pivot 17 ofthelever; the said link 12 is loosely connected to arm 11, and to thisend carries a pin 30 which engages'in an open slot 11 in the end of thearm .11. provided with a projecting lug 18 in which is threaded thescrew 18, the end of which is provided with a block 18", which blockrestson a disc 32, mounted on the shaft 14 which is :the shaft carryingthe cylinder 1 The link 12 is further 7 so that by adjustment of thescrew 18, the downwardtravel of the link 12 is regulated and thereby theamount of pressure of the member 10 upon the doctor 2;

For intermittently raising the doctor so that its rising movement occursjust before and when the gap 1 in the surface of the cylinder 1 ispassing thereunder, a cam 19 rotating synchronously with the cylinder isemployed, and preferably the cam is carried by a disc 20 rotatablymounted on the reduced end 14* of the cylinder shaft 1 1. The cam 19operates with a bowl 21 on the said connecting link 12, so that as themember 20 rotates the cam 19 in passing under the bowl 21 lifts the bowland thereby the link 12, the movement of which is transmitted througharm 11 to the presser member which thereon. is lifted from the. knife,al-

lowing the knife to straighten out by its own springiness and to returnto its preliminary position in which only the thin film of ink is lefton the cylinder.

In cases where a gap does not occur in the cylinder but where there arenon-printing surfaces, the lifting of the doctor will be timed tocorrespond with the moment when such surfaces pass thereunder.

The presser member lO-is preferably reinforced by a metal plate 22 (asclearly shown in Fig. 4) to give it the necessary rigidity, and since itworks substantially over the full length of the doctor, improvedscraping is achieved, and "a longer life for the knife by reason of thepressure being applied centrally.

Adjustment for the cam 19 for the pur-' pose of varying the stroke oflink 12 and thereby the lift of presser member is preferably obtained byproviding the cam 19 with grooved ends which slide on walls of slot 23formed in the disc 20; by means of a screw-threaded stop 24 carried inthe base of the slot the cam may be moved to or from the axis of thecylinder. I

A handle 25 fixed to shaft 7 is preferably employed for lifting thepresser member when cam 19 is not operating; by moving handle 25the-shaft 7 is rotated in its bearings; screws 26 threaded in lugs'7(Fig. 4) fixed on the shaft 7 serve toadjust the edge of the pressermember 10 in position on the doctor between the sup ort 29 and the freeedge of the doctor." gimilarly, screws 27 working in threaded holes ofthe bracket 31 on-the cross shaft I serve to push or retract the doctor2 to or from the cylinder 1.

When the support 29 has been adjusted it is fixedin' selectedposition bylever screw 28.

It will be seen that in' operation of a machine according to thisinvention two ad-- the operating edge of the doctor and its 1 A methodof flexing a doctor supported in contact with the printing surface of aprinting cylinder to effect complete wiping of the printing surface,consisting in applying pressure independent of the doctor support alonga line completely across the doctor from side to side between theoperating edge of the doctor and its support.

2. Apparatus for flexing a doctor-supported in contact with the.printing surface of a printing cylinder to effect complete wiping of theprinting surface, comprising a presser member having a pressing edgeapplied com plctelyacross the doctor from side to side between theoperating edge of the doctor and its support and independent of the support and means for varying the pressure applied by said presser member.

3. Apparatus for flexing a doctor supported in contact with the printingsurface of a printing cylinder to effect complete wiping of the printingsurface, comprising a presser member having a pressing edge appliedacross the doctor from side to side between support, means for varyingthe pressure applied by said presser member, and intermittently operatedmeans for rapidly retracting said presser member from said doctor.

4. Apparatus for flexing a doctor support-- ed in contact with theprinting surface of a printing cylinder to efi'ect' complete wiping ofthe printing surface, comprising in combination with a'pre'sser memberhaving its pressing edge applied across the doctor from side to sidebetween the operating edge of the doctor and its support, a reciprocablemember, of means for intermittently operatsaid reciprocable member insynchronism with revolutions. of the printing cylinder, connecting meansbetween the presser Jnember and the reciprocable member, wheres bythereciprocations of the said member are utilized to retract the pressermember from the doctor, thereby allowing the latter to unflex, and meansforvarying the pressure, applied by said presser'member.

5. Apparatus for flexing a doctor supported in contact with the printingsurface of a printing cylinder to effect complete wiping of the printingsurface, comprising in combination with a reciprocable member and.meansfor operating said member intermittently in synchroni'sm withrevolutions of the printing cylinder, of a presser member having itspressing edge applied across the doctor from side to side between theoperat ing edge of the doctor and its support, connecting means betweenthe presser member and the reciprocable member for positive lycommunicating the movement of the reciprocable member to the pressermember, so that in one direction of movement of the re ciprocable memberthe presser member is forced on to the .doctor to flex it as set forth,

and-in the other direction of movement of v the reciprocable member thepresser member is retracted therefrom to alloys the doctor to unflex,and means for vary ng the pressure applied by said presser member.

6. Apparatus" for flexing a doctor supported in contact with theprinting surface of a printing cylinder to effect complete wiping of theprinting surface, comprising in combination with a reciprocable memberand means for operating said member intermittently in synchronism withrevolutions of the printing cylinder, of a presser memher having itspressing edge applied across the doctor from side to side between theopv crating edge of the doctor and its support, connecting means betweenthe presser memher and the reciprocable member for positivelycommunicating the movements of the reciprocable member to the, pressermember,

so that in one direction of movement of the reciprocable member thepresser member is forced on to the doctor to flex it as set forth,andzin the other direction of movement of the reciprocable member thepresser member is retracted therefrom to allow the doctor to unflex, andmeans for varying' the length of stroke of the reciprocable member bywhich the presser member is forced to the doctor, whereby the pressureapplied by said presser member is variable.-

7. Apparatus for flexing a doctor'sup-' ported in contact with theprinting surface of a printing cylinder 1 to effect complete wiping ofthe printing surface, comprising in combination with a reciprocablemember, cam gear for intermittently raising said member, gravity meansfor effecting its return, and an adjustable stop for varying its travelduring said return, of a presser memthe doctor from side to side betweenthe operating edge of the doctor and its support, a loose connectionbetween said presser member and the reciprocable member,

whereby the action of gravity on the latter applies the pressermember'to the doctor when the said cam gear is inoperative.

8. Apparatus for flexing a doctor supported, in contact with theprinting surface of a printing cylinder to effect complete wiping of theprinting'surface, comprising in combination with arecipro cablemember,

. ber'having its pressing edge applied across cam gear forintermlttently raising said member mcludmg an ad ustable cam forvaryingthe lift im arted to said member, gravity means for effecting itsreturn, and an adjustable stop for varying its travel during saidreturn, of a presser member having its pressing edge applied across thedoctor from side to side between the operat ing edge of the doctor andits support,,a loose connection between said presser member and thereciprocable member, whereby the action of gravity on the latter appliesthe presser member to the doctor when the said cam gear is inoperative.

9. Apparatus for controlling a doctor op erating on the printing surfaceof an intaglio printing cylinder, pressing means for applying, by apreliminary flex of the doctor, a normal adjustment to the said printingsurface, in combination with means for applying direct to the doctorfrom side to side between the operating edge of the doctor and itssupport, a force which efiiects a further flexing of the doctor toobtain the scraping contact proper, and intermittently operatedmechanism for removing the pres-' sure of the said force at such tlmesas a non-I printing surface passes under the doctor reinstating saidnormal adjustment.

1(). The combination in an intaglio printing machine having a metalprinting sheet attachment to the cylinder, of a doctor normally adjustedby regulating screws to give a slight preliminary flex thereto, a linkin-.

termittently reciprocated diametrically of the cylinder, of a pressermember having its pressing edge applied across the doctor from side toside between the operating edge of the doctor and its support, and anoper-- ture.

' MALCOLM OWEN.

